Was the forecast right for Boston on Mon Sep 14?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
13 days out, 4 models put Boston's Mon Sep 14 high anywhere from 70° to 73°; by the final call the field had settled to a median of 72°. The day verified at 74° against the BOS observations — cloudy.
GEM landed closest, off by 0.6°. ECMWF ran 3° cold.
What every model said, at every lead
Daily-high calls for Mon Sep 14 as each model's runs approached it — the last archived run per day. NBM and The Spread's own blend are consensus products and stay out of these ranges and rankings; the Boston scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-08-30 | — | 65° | — | — | 70° | — | — | 65–70° |
| 14d · 2026-08-31 | 80° | 77° | — | — | 72° | — | — | 72–80° |
| 13d · 2026-09-01 | 73° | 72° | 70° | — | 71° | — | — | 70–73° |
| 12d · 2026-09-02 | 80° | 74° | 81° | — | 80° | — | — | 74–81° |
| 11d · 2026-09-03 | 76° | 93° | 65° | — | 80° | — | — | 65–93° |
| 10d · 2026-09-04 | 76° | 71° | 75° | — | 71° | — | — | 71–76° |
| 9d · 2026-09-05 | 67° | 76° | 72° | — | 85° | — | — | 67–85° |
| 8d · 2026-09-06 | 72° | 79° | 92° | 70° | 85° | — | — | 70–92° |
| 7d · 2026-09-07 | 73° | 70° | 77° | 72° | 84° | — | — | 70–84° |
| 6d · 2026-09-08 | 72° | 72° | 75° | 71° | 78° | 77° | — | 71–78° |
| 5d · 2026-09-09 | 70° | 74° | 80° | 72° | 78° | 84° | 84° | 70–84° |
| 4d · 2026-09-10 | 71° | 73° | 75° | 67° | 70° | 71° | 75° | 67–75° |
| 3d · 2026-09-11 | 73° | 73° | 78° | 70° | 70° | 73° | 75° | 70–78° |
| 2d · 2026-09-12 | 72° | 73° | 74° | 70° | 72° | 70° | 74° | 70–74° |
| 1d · 2026-09-13 | 72° | 72° | 72° | 74° | 70° | 73° | 75° | 70–75° |
| 0d · 2026-09-14 | 72° | 73° | 71° | 73° | 71° | 72° | 73° | 71–73° |
| actual | 74° |
Read it honestly
This is one date, not a league table. A model can win a day it deserved to lose; rankings only mean something over a window. For that, see which model has been most accurate in Boston — or every city The Spread scores.
Forecasts are what each model's archived runs said at the time, captured at The Spread's sweep times — never reconstructed after the fact. Truth is the BOS observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.